A little noticed surveillance technology, designed to track the movements of passing drivers, is fast proliferating America’s streets. Automatic license plate readers (ALPR) mounted on police cars or on objects like road signs and bridges, use small, high-speed cameras to photograph every passing car.

This system photographs every license plate it encounters - capturing thousands of cars’ information per minute – and uses software to read the number, add a time and location stamp, and then record the information in a database. A computer checks the information in these pictures against police department databases. If a scanned plate matches information in the database, an officer is alerted.

License plate readers can be a useful tool for police officers, helping them recover stolen cars and arrest people with outstanding warrants. However, the spread of these scanners is creating what are, in effect, government location tracking systems recording the movements of many millions of innocent Americans in huge databases. 

To protect the privacy of millions of Americans, there is a dire need for rules to make sure that this technology isn’t used for unbridled government surveillance.

So why should you care?

License plate tracking information can be very revealing. While one snapshot at one point might not seem sensitive, as blankets of plate readers cover our streets, and as the government stores data for longer periods of time, the technology quickly morphs into a powerful tracking tool that can reveal extremely sensitive information about who we are and what we do.

A person who knows all of another’s travels can deduce whether he is a weekly churchgoer, a heavy drinker, a regular at the gym, an unfaithful husband, an outpatient receiving medical treatment, an associate of particular individuals or political groups — and not just one such fact about a person, but all such facts.

Virtually all of the data license plate readers gather is of innocent people, not just of people suspected of crimes. In our society, it is a core principle that the government does not invade its citizens' privacy and store information about their innocent activities just in case they do something wrong.

New Legislation

Fortunately, recently introduced legislation aims to both protect Michiganders’ privacy rights and preserve the use of the technology for unobjectionable and beneficial law enforcement purposes.

This week, the Michigan House Criminal Justice Committee will hold a hearing on Representative Sam Singh’s (D-East Lansing) House Bill 4981, a bill that would regulate the use of automatic license plate readers.

The ACLU of Michigan is in support of this important legislation, which adheres to the following principles:

  1. License plate readers may be used by law enforcement agencies only to investigate hits and in other circumstances in which law enforcement agents reasonably believe that the plate data are relevant to an ongoing criminal investigation.
  2. The government must not store data about innocent people for any lengthy period. Unless plate data has been flagged, retention periods should be measured in days or weeks, not months and certainly not years. This is the key to regulating license plate readers.
  3. People should be able to find out if plate data of vehicles registered to them are contained in a law enforcement agency’s database.
  4. Law enforcement agencies should not share license plate reader data with third parties that do not follow proper retention and access principles. They should also be transparent regarding with whom they share license plate reader data.
  5. Any entity that uses license plate readers should be required to report its usage publicly on at least an annual basis.

By Merissa Kovach, Field Organizer 


Additional Resources
The ACLU has done extensive research on the use of automatic license plate readers, creating comprehensive reports, data and talking points. Check out the full story on this threat to your privacy at the National ACLU

You Are Being Tracked: How License Plate Readers Are Being Used to Record Americans' Movements